1. Field of Invention
The present invention pertains to stuffing boxes and scaling assemblies for shafts or rods, particularly well pump rods.
2. Background
Many producing oil wells do not have sufficient well pressure for a natural flow of the well fluid. As a result, some means must be utilized for lifting the well fluid to the earth's surface. Many of the producing oil wells utilize pumping means actuated by a reciprocating rod. The pumping unit itself is normally installed near the bottom of the well bore and is actuated by a string of rods extending downwardly through the well bore from the surface of the ground. The uppermost rod which projects from the wellhead is commonly called the polished rod. A stuffing box is usually secured to the wellhead around the polished rod to prevent leakage of the pumped well fluid from around the polished rod. Packing seals or packing rings of various types are normally disposed within the stuffing box and bear against the outer periphery of the polished rod to provide a sealing engagement there around.
Due to the abrasive sand particles present in crude oil and poor alignment between the wellhead and stuffing box, leakage of crude oil from the stuffing box is common in some applications. It is especially a problem with heavy crude oil wells in which the oil is often produced from semi-consolidated sand formations since loose sand is readily transported to the stuffing box by the viscosity of the crude oil. The reciprocation of the rod with respect to the packing rings wears the inner periphery of the packing rings, thus requiring frequent manual attendance at the stuffing boxes to assure an efficient sealing action around the polished rod.
Oftentimes, the packing rings must be replaced. Existing stuffing boxes do not provide a ready way to remove, replace or adjust old packing seals. In existing stuffing box designs, old packing rings are contained within an immovable cylindrical retainer or body exposing only the top surface of the uppermost packing ring. Thus, to redress the packing box and replace the old packing rings, the old rings must be “dug out” from an opening at the top of the cylinder. Older packing seals can become hardened or brittle over time, making their removal difficult and time consuming.
The embodiments of the present invention described herein provide opportunities for improvement in repair, redress, replacement or adjustment of the packing rings.